Metalmorphosis: the changing face of metal detection

Recent developments in metal detection technology have made this quality-control process an increasingly important safeguard against contaminant food scares.

A number of recent and well-publicised food scares have highlighted the often-costly consequences of ineffectual end-of line inspection routines. The upshot of these damaging oversights has been an increased public awareness of, and interest in, food preparation.

Conscious of the stigma attached to food scares, many processors are responding by introducing additional quality checks that safeguard their products against unwanted contaminants. Yet, surprisingly, some food manufacturers are bucking this trend by failing to supplement their inspection regimes with metal detection equipment.

"Most food processors install metal detecting equipment as part of their due diligence procedures," says Tony Symes, product manager for metal detection at Loma Systems. "However, we've been staggered to discover that around 5% of companies are prepared to risk a major food scare by not having metal detectors."

One possible reason for this apparent apathy is a lack of any legislation governing metal detection in the food-processing sector, although such laws do exist in Germany. Tony says metal detectors are vital to any process line. "Metal detectors should be an integral part of food processors' due diligence systems, policed overall by Hazard Analysis Critical Control Point (HACCP) procedures. The latest systems are extremely easy to set up, easy to maintain and available in formats to suit a wide range of products and processes. The developments have been so marked that even companies which have already invested in the technology will notice considerable changes in the newest models."

Metal works

As well as pinpointing the minority of companies who are yet to introduce metal-detecting systems, Loma's market research has also revealed that up to 10% of Loma Press Release companies have an inadequate number of detection machines and over 25% are failing to use their equipment to its full potential. Tony suggests that a number of factors could explain this. "While many of these companies will no doubt introduce metal detection, others are happy to just get away with it," he says. "This could be because they believe metal detectors are expensive."

Tony also suggests that developments in modern detection technology will enable more firms to introduce metal-detecting routines. "Until recently, some companies' operating procedures were not suitable for metal detectors. In most cases, this is no longer the case as the latest systems incorporate robust designs and enhanced detection capabilities that easily meet the challenges of the most demanding applications."

To illustrate this point, Tony says one of the most important developments has been the introduction of metal detectors designed specifically for hostile production environments found in the meat, poultry and fish-processing industries. In particular, these state-of-the-art systems feature resin skins which protect the system's coils and fully welded process plastic liners that seal the detector's housing.

Tony also cites dual-frequency detectors as another major innovation that will convince even more firms to invest in the latest metal-detection equipment. These highly advanced systems offer up to 49 frequencies, ranging from 31.25 kHz to 425.0 kHz, meaning the ideal frequency can be selected to meet specific detection requirements. This is especially important when several different types of product with discrete product signals are processed, or when various dry products utilise both PE and metallised films. Both can be serviced with dual-frequency detectors without sacrificing sensitivity.

Another reason given by Tony for not implementing a metal detection policy is the high percentage of unskilled workers who require training to ensure that all products are inspected to the same standard. The assumption, Tony says, is that metal detectors are difficult to use, which, he argues, is no longer the case.

"Significant progress has been made in the simplification of metal detection. For instance, Performance Validation Systems (PVSs) automate the testing procedure through operator prompts and alarm signals. In this way, the metal detector, rather than the operator, determines if the test has passed or should be failed."

Reducing risk

Tony's reasoning seems sound. Metal detection is an evolving technology that is becoming increasingly applicable to a growing number of sectors. Moreover, it is a cost-effective way of securing food-processing companies against metal-contaminant food scares. For Tony, the developments affecting metal detection mean excluding these systems from processing lines is a risky business. "I'm amazed that some companies are still willing to risk not having metal detection. It's even more astounding when you consider the advancements we've made in system robustness and detection sensitivity."